发射线分类和SDSS中活动星系核类星系的性质
Emission line taxonomy and the nature of AGN-looking galaxies in the SDSS
摘要：
像SDSS这样的大规模光谱测量已经彻底改变了我们研究AGN及其与所在星系关系的方式。任何此类研究的第一步是根据发射线比率确定不同类型活动星系核的样本。这个看似简单的步骤涉及决定使用哪种分类方案和数据质量审查。具有弱发射谱线的星系通常被放在一边或单独处理，因为人们不能完全将它们归类到标准的恒星形成，Seyfert的LINER类别。这一贡献总结了替代分类方案，其中包括这一非常众多的人口。然后，我们研究如何恒星形成的历史和物理性质的主机不同的类，并提出令人信服的证据表明，在大多数的LINER类系统的SDSS的发射线不是由黑洞吸积。这些数据完全符合它们是星系，其古老的恒星提供了解释它们的线比和光度所需的所有电离能力。这样的退休星系应该在发射线分类中占有一席之地。
英文摘要：
Massive spectroscopic surveys like the SDSS have revolutionized the way we study AGN and their relations to the galaxies they live in. A first step in any such study is to define samples of different types of AGN on the basis of emission line ratios. This deceivingly simple step involves decisions on which classification scheme to use and data quality censorship. Galaxies with weak emission lines are often left aside or dealt with separately because one cannot fully classify them onto the standard Star-Forming, Seyfert of LINER categories. This contribution summarizes alternative classification schemes which include this very numerous population. We then study how star-formation histories and physical properties of the hosts vary from class to class, and present compelling evidence that the emission lines in the majority of LINER-like systems in the SDSS are not powered by black-hole accretion. The data are fully consistent with them being galaxies whose old stars provide all the ionizing power needed to explain their line ratios and luminosities. Such retired galaxies deserve a place in the emission line taxonomy.
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